Industrial enzymes have generally been formulated as particulate solids (e.g. in powder or granulated form, optionally with a coating of some kind) or in the form of a water-based solution.
A number of solid formulations (e.g. enzyme powders) have the disadvantage that dust formation readily takes place, which--unless special precautions are taken may result in contamination of the surrounding environment and thereby pose a risk to the health of persons handling such compositions.
Water-based, liquid enzyme formulations essentially eliminate the risk of dust formation. owing to the fact that practically all enzymes exert their activity in the presence of water it is generally not feasible to prepare storage-stable formulations comprising free (e.g. unencapsulated or uncoated) enzymes.
Currently available water-based liquid enzyme formulations have a relatively short time span, within which it is possible to operate, as the residual enzymatic activity is reduced to an unacceptable low level after a few weeks of storage if not stored under cooling.
Feng Xu et al, (1996), Biochimica et Biophysica Acta, 1292, p. 303-311 shows that the stability of various laccases is dependent on the pH and the temperature after pre-incubation with ABTS for 1 hour.
Palmiert et al., (1993), Applied Microbiol. Biotechnol., 39, p. 632-636, shows that a specific laccase incubated at 25.degree. C. is more stable at pH 7 than at pH 3 for a period of 300 minutes (i.e. 6 hours).
Thus, there is a need for liquid formulations comprising a laccase which are storage-stable for a period of more than one day. The present invention provides formulations fulfilling such a need.